The invention relates to a closed hollow support made of sheet metal having two support sections, which form a hollow space and are welded together in an area of their longitudinal edges. Two stiffening sections, which reinforce the hollow support are arranged in the hollow space of the hollow support and extend in longitudinal direction of the hollow support and are welded to the hollow support. This general type of hollow support is known from GB-PS 10 10 678.
These type of closed hollow supports are mainly used in vehicles of various types as box girders. For the purpose of a stabilization with respect to buckling and torsional movements and vibrations, these closed hollow supports are generally stiffened in various fashions According to GB-PS 10 10 678, the closed hollow support is formed by two support sections, welded together along their longitudinal edges, and has a hollow space which is enclosed by the support sections. Two stiffening sections, which stiffen the hollow support and extend in longitudinal direction of the hollow support, are welded into the hollow space. The welding of the stiffening sections can onlY take place successively, is inconvenient and results in insufficient stability under high stress, for example, as a hollow support of a vehicle during an accident.
Another possibility for stiffening a closed hollow support is described in DE-OS 19 03 327. There a continuous main support member, in the junction point, is stiffened by a stabilizing member which is placed on it on the outside and corresponds to its shape. Both members are welded together with one another at holes located in the stabilizing member. As a result, the outer contour of the closed hollow support is not smooth and may have to be trimmed or primed
The instant invention is based on the object of further developing a closed hollow support of the above general type in such a manner that it is more stable and easier to manufacture.
According to the invention, this object is achieved by having each support section welded together with a stiffening section which has a meandering shape in its cross-section. The stiffening sections are arranged approximately mirror-invertedly in the hollow space and, in turn, are connected at mutual contact surface extending in the longitudinal direction of the hollow support. The connections are reached through opposing holes in at least one support section, which is assigned to the area of these connections.
The stiffening sections, which are connected with one another and are mounted in the closed hollow support, form a second hollow support which is located on the inside and utilizes the structure clearance. By welding-together each of the stiffening sections with the respective pertaining support section, the section part of each support half are prepared to be fixedly connected with one another. The mutual connection of the two interior stiffening sections through the wall of one of the support sections provides this connection and increases the stability of the closed hollow support by many degrees. The stiffening sections, after the support sections were first connected with the pertaining stiffening section and then with one another, can be fixedly connected on the inside through access holes.
When the closed hollow support is preassembled, the respective stiffening section is welded simultaneously to both support sections. The thus created hollow support halves are pressed together subsequently and welded together along their longitudinal edges. The connecting of the mutual contact surfaces of the stiffening sections advantageously takes place during the same working cycle in which the longitudinal edges of the support sections are welded together.
The stiffening sections, in the preassembled condition, together in transverse direction to the contact surface, have a larger width than the corresponding width of the hollow area of the closed hollow support. When the two hollow support halves are pressed together for the welding-together of the longitudinal edges, the larger width of the stiffening sections causes a contact pressure onto the mutual contact surfaces, permitting a better indirect welding-together at this point.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.